Liquid Natural Gas (LNG) vehicle pressure vessels are widely used in heavy duty trucking operations. U.S. Pat. No. 5,421,161 describes an improved cryogenic fuel tank system. The system is particularly useful in horizontal cryogenic tanks (i.e. pressure vessels), such as those containing low-density fluids like LNG. However, while the system of the '161 patent works quite well for reducing pressure inside a pressure vessel through an economizer circuit, it actually limits the pressure vessel's ability to build pressure in mobile applications because it limits the rate of backflow of product to the vessel.
In view of the foregoing, there is a need for an improved cryogenic fuel pressure vessel system that is particularly suited for horizontal fuel pressure vessels.